CVE-2000-0586: Buffer overflow in Dalnet IRC server 4.6.5 allows remote attackers to cause a denial of service or execute arb

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HIGH 10.0DOWNGRADE

CVE-2000-0586 is a high-severity flaw (CVSS 10.0) affecting ircd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Buffer overflow in Dalnet IRC server 4.6.5 allows remote attackers to cause a denial of service or execute arbitrary commands via the SUMMON command.

Why this priority

Critical severity
EPSS top 8%: very likely to be exploited
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	10.0 (High)
EPSS exploit chance	4.8% (top 8%)
CISA exploited list	No
Published	2000-06-29
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: dalnet

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2000-06-29 04:00 UTCPublished CVE record published
2026-06-16 21:52 UTCUpdated Record last modified

dalnet ircd DOWNGRADE

Affected: 4.6.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.6.5

1. Check installed version

apt-cache policy ircd || rpm -q ircd || ircd --version

2. No fixed release: DOWNGRADE to a release before 4.6.5 (Debian / Ubuntu)

apt-cache madison ircd sudo apt install ircd=<VERSION_BEFORE_4.6.5> sudo apt-mark hold ircd

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ircd sudo dnf downgrade ircd-<VERSION_BEFORE_4.6.5> sudo dnf versionlock add ircd

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: DALnet Bahamut IRCd 4.6.5 - 'SUMMON' Remote Buffer Overflow

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2000-0586?

ircd: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2000-0586 being exploited?

CVE-2000-0586 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2000-0586 affect?

CVE-2000-0586 affects ircd. Severity is high (CVSS 10.0). Buffer overflow in Dalnet IRC server 4.6.5 allows remote attackers to cause a denial of service or execute arbitrary commands via the SUMMON command.

How urgent is CVE-2000-0586?

Priority 63/100. Critical severity; EPSS top 8%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2003-0478 HIGH 10.0 DOWNGRADE DOWNGRADE Format string vulnerability in (1) Bahamut IRCd 1.4.35 and earlier, and other IRC daemons based on Bahamut inc

References

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